1. Field of the Invention
This invention relates generally to automatic machine tools programmable to perform multiple machining functions on a workpiece, and more particularly, to automatic machine tools having loading and unloading devices, automatic workpiece turnover means, and automatic operation of a multitude of machining functions incorporated in a completely integrated system.
2. Description of the Prior Art
Automated machine tools are well-known in the art, that perform a variety of cutting functions such as milling, drilling, threading, tapping, etc. on a workpiece. These machines are normally provided with a tool carrousel that has numerous cutting tools mounted thereon for performing the variety of functions of the machine. The tool holder is generally a rotatable tool spindle mounted in a drill head which is adjustably mounted on a vertical column or quill for vertical movement. The tool spindle is mounted for rotation relative to the quill and is moveable axially with respect to the drill head. Additionally, the workpiece is secured to a worktable that is moveable in a x-y horizontal plane for providing a variety of positions to perform the various cutting operations.
The machining operation is performed by the rotatable tool spindle rotatably mounted in a spindle head and arranged to be shifted vertically with respect to the workpiece. Precision cutting is performed, such that a hole center may be precisely located with respect to the axis of the rotatable tool spindle and the combined movement of the worktable in its horizontal plane of movement. During the machining operation, the spindle is rotated at a pre-selected cutting speed and is feed downwardly by the drill head on the quill at a predetermined feed rate. The cutting tool is removably mounted in a chuck which is supported by the lower end of the rotatable tool spindle, and forms a part thereof. Additionally, a tool changer is adapted to remove the used tool from the chuck at the end of a cutting operation and replace the used tool with a pre-selected new tool in an automatic manner that eliminates lost time associated with manual tool changing operations.
All of these machine functions are carried out in rapid efficient manner in order to bring about the most efficient operation of the machine tool. The automatic control of the machine tool is provided by a numerical control system operating under the control of a punched tape or other memory device which regulates the table so as to locate a cutting center with respect to the axis of the tool, the automatic selection of the spindle speed, the spindle feed rate on the quill, and other machine functions.
Automatic loading or unloading features, and part turnover are usually not provided in automatic machine tools. It is often feasible to clamp the workpiece in a fixture outside of the machining area and slide it on rails into machining position after clamping. Also, after the workpiece is in machine position, present automated machine tools do not have the capability to rotate the part for additional machining.
It would be desirable if an automatic machine had the capability to select a workpiece from a stack of material and completely perform all machining functions. These functions should include unloading the workpiece from a stack of material, securing the workpiece to the worktable in preparation for a machining function, cleaning off scrap chips, rotating the workpiece, drilling holes at any angle, turning the workpiece over 180.degree., performing a variety of automated machining functions, releasing the workpiece from the worktable, removing the workpiece from the machining area, and finally selecting a new workpiece from a stack of material.
Such a machine tool having a much greater degree of automation is a completely integrated system and provides much more efficiency in machining operations without manual intervention.